Microsoft claims that LINQ to SQL is not a dead technology, despite their focus on Entity Framework. From Redmond Developer News:
Tim Mallalieu, the program manager for both LINQ to SQL and the Entity Framework, ... says Microsoft anticipated the backlash but said both data access interfaces will be better off for this move. For those who don't think the Entity Framework is a suitable replacement, Mallalieu said stay tuned.
"There's some pretty nifty stuff we're doing in the beta 2 time frame that we are not speaking about as yet, I think it will give you a better experience and will reduce the anxiety that people have around the Entity Framework," Mallalieu said. "In terms of capabilities, I think will make the overall integrated experience of ASP.NET, Dynamic Data, MVC and these other things easier, we did a little bit of triaging and feedback, there is some valid feedback around complexity in the Entity Framework and we are doing things to address that. "
Especially in light of the fact that LINQ to SQL is specific to SQL Server, I think it's best to wait a while to see what happens with Entity Framework. Note that there are quite a few folks who aren't happy with the way it has turned out so far.